Английский разговорный словарь (основной) - nucleus

ˈnju:klɪəs n. (pl. nuclei) 1 a the central part or thing round which others are collected. b the kernel of an aggregate or mass. 2 an initial part meant to receive additions. 3 Astron. the solid part of a comet's head. 4 Physics the positively charged central core of an atom that contains most of its mass. 5 Biol. a large dense organelle of eukaryotic cells, containing the genetic material. 6 a discrete mass of grey matter in the central nervous system. [L, = kernel, inner part, dimin. of nux nucis nut]